From patchwork Thu Apr 13 21:39:28 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Heiner Kallweit X-Patchwork-Id: 13210685 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 39026C77B61 for ; Thu, 13 Apr 2023 21:39:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229674AbjDMVjd (ORCPT ); Thu, 13 Apr 2023 17:39:33 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55056 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229596AbjDMVjc (ORCPT ); Thu, 13 Apr 2023 17:39:32 -0400 Received: from mail-wm1-x331.google.com (mail-wm1-x331.google.com [IPv6:2a00:1450:4864:20::331]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 184934489 for ; Thu, 13 Apr 2023 14:39:31 -0700 (PDT) Received: by mail-wm1-x331.google.com with SMTP id q5so9335346wmo.4 for ; Thu, 13 Apr 2023 14:39:31 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20221208; t=1681421969; x=1684013969; h=content-transfer-encoding:subject:from:cc:to:content-language :user-agent:mime-version:date:message-id:from:to:cc:subject:date :message-id:reply-to; bh=Zz78mqpdfFC3Sk8OAfqHSfILvBJAp1baciGW5F5+h8k=; b=IDnGEJor8dFMRpJYOLeWa34GKvzYJF5UvcYzSXW0ZIX7NgNwXZ+YDXdHFuUp+TBIDz ybQWt4inebsZk4uk6GQoRr3kO/J8Cuum32ICtc6GnxMN0dM1sXX3s3L1tv1w4WRgf2oM hYJlv5OAhsUIu0/LSvluDccvCZ6XcAivd1o5g9vPLpefWVZKeDOBFJSabOIQ+pZvR1Jy jTdhvnmBFFrr1GGUw0/1zL3A1qZlVbzR93mWdKxMCG43o+vfH88Fl6kFQUUjupy5mA/g 8CujNVyQb6uifL6AqrkfFlfzpl6N1y1Q+/jZqDqzxm/jFkCdjekhtkCEDIBRWagJtkbf 1KiA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1681421969; x=1684013969; h=content-transfer-encoding:subject:from:cc:to:content-language :user-agent:mime-version:date:message-id:x-gm-message-state:from:to :cc:subject:date:message-id:reply-to; bh=Zz78mqpdfFC3Sk8OAfqHSfILvBJAp1baciGW5F5+h8k=; b=kU2V2cS75EnvocKG2eTDfODC0NFHDxQAIOoZBRM497UEfNW54L0P9wOw8j28FFUG8A TMNotyfvoDLih5vyWq3B6DNB51dCRnfqC3NcMJZXnc3uGUne6qKMDJZiY20Vy5TGay/h N0nYcADRH1xCaii7yd8cSNdv6r8Uq2MyJtr95bu/PwN1yA7fWYvD8otQobVWuy2q20// y6gP5PRQ4owRmxFR8jb/U/Cqc8fru5Y/04QcLatRB7X60Up1/iax/fZ4/XjIPLh91Xx9 s4efu5f8jXS2JUUQ8Xh/EoW0pz1l1FABFeiSuXmzLVy7VLWa/MAKvT3IXnrYMTFZNC/D A5cA== X-Gm-Message-State: AAQBX9eJ4LDGQj+D+pXi1jXxPXNQIPs8ROpxQS8N7psevxCMawLhJxS/ vZzgnhM9isszZMgHYOb69YQ= X-Google-Smtp-Source: AKy350Y9OGQ9uq78btrzeRKxw7uEtYohEgTHzD6TzAkcgvyYvGUQrSLRt3fNTO8ShhE6pY/R714vrw== X-Received: by 2002:a05:600c:ac6:b0:3f0:ad48:6ef with SMTP id c6-20020a05600c0ac600b003f0ad4806efmr1972979wmr.15.1681421969398; Thu, 13 Apr 2023 14:39:29 -0700 (PDT) Received: from ?IPV6:2a01:c22:738e:4400:f580:be04:1a64:fc5e? (dynamic-2a01-0c22-738e-4400-f580-be04-1a64-fc5e.c22.pool.telefonica.de. [2a01:c22:738e:4400:f580:be04:1a64:fc5e]) by smtp.googlemail.com with ESMTPSA id k15-20020a05600c1c8f00b003ede2c59a54sm6501346wms.37.2023.04.13.14.39.28 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 13 Apr 2023 14:39:29 -0700 (PDT) Message-ID: <4eb4755b-7a06-6cd9-7c9d-6d088d05ab19@gmail.com> Date: Thu, 13 Apr 2023 23:39:28 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:102.0) Gecko/20100101 Thunderbird/102.10.0 Content-Language: en-US To: Michael Turquette , Stephen Boyd Cc: linux-clk@vger.kernel.org, Martin Blumenstingl From: Heiner Kallweit Subject: [PATCH] clk: change clk_hw_create_clk() to avoid being unable to remove module Precedence: bulk List-ID: X-Mailing-List: linux-clk@vger.kernel.org With clk_hw_create_clk() we have the problem that module unloading is impossible if consumer and provider module owner are the same and refcount is incremented. See also following comment in __clk_register(). /* * Don't call clk_hw_create_clk() here because that would pin the * provider module to itself and prevent it from ever being removed. */ I think this also affects any usage of clk_hw_get_clk(). To deal with this let's increment the refcount only if owners are different. Signed-off-by: Heiner Kallweit --- drivers/clk/clk.c | 20 ++++++++++++++++---- 1 file changed, 16 insertions(+), 4 deletions(-) diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c index 27c30a533..e9bf961d4 100644 --- a/drivers/clk/clk.c +++ b/drivers/clk/clk.c @@ -103,6 +103,7 @@ struct clk { unsigned long max_rate; unsigned int exclusive_count; struct hlist_node clks_node; + bool put_core_owner; }; /*** runtime pm ***/ @@ -3969,6 +3970,7 @@ struct clk *clk_hw_create_clk(struct device *dev, struct clk_hw *hw, { struct clk *clk; struct clk_core *core; + struct module *owner; /* This is to allow this function to be chained to others */ if (IS_ERR_OR_NULL(hw)) @@ -3980,9 +3982,18 @@ struct clk *clk_hw_create_clk(struct device *dev, struct clk_hw *hw, return clk; clk->dev = dev; - if (!try_module_get(core->owner)) { - free_clk(clk); - return ERR_PTR(-ENOENT); + owner = (dev && dev->driver) ? dev->driver->owner : NULL; + /* + * Avoid being unable to remove module if consumer and + * provider have the same owner. + */ + if (owner != core->owner) { + if (try_module_get(core->owner)) { + clk->put_core_owner = true; + } else { + free_clk(clk); + return ERR_PTR(-ENOENT); + } } kref_get(&core->ref); @@ -4560,7 +4571,8 @@ void __clk_put(struct clk *clk) clk_prepare_unlock(); - module_put(owner); + if (clk->put_core_owner) + module_put(owner); free_clk(clk); }